Creation and visualization of computer graphics takes an ever increasing importance in diverse fields of computing such as computer aided design (CAD), architectural walkthroughs, simulations, medical visualization and computer games. The visualization of computer graphics also often requires that interaction with the model takes place at an interactive frequency of greater than 10 frames per second.
A common trend for computer graphics is the increasing amount of complexity and therefore size of the computer graphic models. The initial 3D models are computationally very expensive and thus require specialized graphics systems to handle, furthermore they are generally never able to be handled interactively. The development of computer hardware is not likely to provide interactive handling of those 3D models since the size of the computer graphics and the size of the secondary computer memory is increasing at faster rates than the development of thereto related hardware. 3D models are with few exceptions represented using polygonal meshes. These meshes are typically not optimized for display or simulation performance. In most applications, the initial meshes can usually be replaced by optimized simplified versions that are approximations with far fewer faces, or containing other properties that make them more suited for particular applications such as those mentioned earlier.
For example, a visual image that includes a large scene of a computer game, such as a building interior, a city, mountain, and the like, may involve millions of polygons that need to be drawn. Drawing such a large number of polygons may be a task that is beyond the capacity of many of today's computer hardware systems. One solution to this problem recognizes that usually only a small part of such a scene is actually visible. That is, many of the polygons that comprise the scene may be hidden or occluded by other polygons, or even too far from the viewpoint to be fully recognized.
For such a purpose and specifically in regards to complex polygon representations, there is a trend to manually create simplified representation resembling the complex polygon representations but introducing a lower computational cost for use in the determination process during polygon occlusion (often referred to as occlusion culling). By occlusion culling, where object which are hidden behind in other objects in the virtual scene are not put into the rendering pipeline, the amount of data which will be sent to the hardware is reduced. Hence, by such a process it is possible to further improve rendering of the scene. Moreover, to optimize the rendering of objects in virtual environments, shadows cast by object may often be calculated using the simplified representations due to the high detail level of the original virtual object.
However, the simplified versions are generally created manually by a graphical artist and their creation is labor intensive and the quality of the simplified version will depend on the skill of the artist. Hence, the manual creation of the simplified representations is a tedious process and slows down as well as increases the cost when e.g. producing a computer game or similar. In addition, the quality of the resulting simplified polygon representation is limited by the skill of the graphics artist. Accordingly, it would be desirable to allow for automation of the forming of a simplified representation, possibly being useful in an occlusion culling process.